Fluoride‐Free Synthesis of 2D Titanium Carbide (MXenes) Assisted by scCO₂‐Based Ternary Solution

Abstract 2D MXene‐Ti₃C₂T_x holds great promise in various electronic applications, especially for electromagnetic interference (EMI) shielding devices and supercapacitors. Ti₃C₂T_x synthesis typically involves the use of hazardous fluorine‐containing chemicals that can result in the formation of inert fluoride functional groups on the surface of Ti₃C₂T_x, severely degrading its properties and posing a threat to the performance of electron transfer among electrical devices. Herein, a supercritical carbon dioxide‐based ternary solution (scCO₂/DMSO/HCl) to produce fluoride‐free Ti₃C₂T_x in mild conditions (via 0.5 m HCl, 20 MPa, 32 °C) is reported. The fluorine‐free Ti₃C₂T_x films electrode presents an excellent gravimetric capacitance of 320 F g⁻¹ at 2 mV s⁻¹ in 1 m H₂SO₄. Besides, it is demonstrated that fluorine‐free Ti₃C₂T_x films exhibit outstanding EMI shielding efficiency of 53.12 dB at 2.5 µm thickness. The findings offer a mild and practical approach to producing fluoride‐free Ti₃C₂T_x and open opportunities for exploring MXenes’ potential applications in various fields.